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High Temperature Material Processes (An International Quarterly of High-Technology Plasma Processes)

An International Journal

ISSN for PRINT: 1093-3611

Institutional price:	$604.00
Issues per year:	4

Best Paper Award Selection - Editorial Board Site

2006, Volume10

168 pages

DOI: 10.1615/HighTempMatProc.v10.i1

Issue price - $155.00

Thermal cycling behavior of Yttria Stabilized Zirconia and Lanthanum Zirconate as graded and bilayer EB-PVD thermal barrier coatings

K. Bobzin
Surface Engineering Institute (IOT), RWTH University of Technology Aachen, Augustinerbach 4-22, 52066 Aachen, Germany

Erick Lugscheider
Werkstoffwissenschaften Lehr und Forschungsgebeit der RWTH Jiilicher Sir. 342-352 52070 Aachen; Surface Engineering Institute (IOT), RWTH University of Technology Aachen, Augustinerbach 4-22, 52066 Aachen, Germany

N. Bagcivan
Surface Engineering Institute (IOT), RWTH University of Technology Aachen, Augustinerbach 4-22, 52066 Aachen, Germany

ABSTRACT

Traditionally Yttria partially stabilized Zirconia (YPSZ) coatings are used as thermal barrier coatings (TBCs) on chambers. More and more often, they are applied on turbine blades. Investigations on some various materials with perovskite, spinel and pyrochlore structures have shown a great potential of Lanthanum Zirconate (pyrochlore) as thermal barrier coatings. In this work, Lanthanum Zirconate has been developed as a TBC using Electron Beam Physical Vapour Deposition (EB-PVD). TBCs deposited by EB-PVD exhibit a columnar grain microstructure, which is able to better balance the difference in thermal expansion between the base material and TBC during thermal cycle and hence improved the TBC lifetime. Two different coating architectures were developed for the TBCs. First a bilayer TBC consisting of YSZ and Lanthanum Zirconate was deposited. In the second approach a graded TBC with a transition from YSZ to Lanthanum Zirconate was deposited. The thermal cycling behavior of these coatings on Inconel Alloy 600 was investigated by a thermal cycling test at 1050 °C. Additionally, the coatings were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The results of thermal cycling test showed an increase in the number of cycles before fatigue from 1380 cycles for YSZ to 3390 cycles for the graded YPSZ/Lanthanum Zirconate and 4140 cycles for the bilayer YSZ/Lanthanum Zirconate.